74 lines
2.0 KiB
Markdown
74 lines
2.0 KiB
Markdown
## MQTT
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MQTT 是一种基于发布/订阅（publish/subscribe）模式的“轻量级”通讯协议 。本章介绍如何在 RT-Thread MicroPython 上使用 MQTT 功能，使用到的模块为 `umqtt.simple` 模块。
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### 获取并安装 umqtt.simple 模块
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同样的可以使用包管理中的两种方式来获取，使用 upip 安装的方式可使用 `upip.install("micropython-umqtt.simple")`如图：
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### umqtt.simple 模块的使用
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#### MQTT 订阅功能
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- 使用 `iot.eclipse.org` 作为测试服务器
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```python
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import time
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from umqtt.simple import MQTTClient
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# Publish test messages e.g. with:
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# mosquitto_pub -t foo_topic -m hello
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# Received messages from subscriptions will be delivered to this callback
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def sub_cb(topic, msg):
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print((topic, msg))
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def main(server="iot.eclipse.org"): # 测试 server 为 iot.eclipse.org
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c = MQTTClient("RT-Thread", server)
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c.set_callback(sub_cb)
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c.connect()
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c.subscribe(b"foo_topic") # 订阅 foo_topic 主题
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while True:
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if True:
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# Blocking wait for message
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c.wait_msg()
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else:
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# Non-blocking wait for message
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c.check_msg()
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# Then need to sleep to avoid 100% CPU usage (in a real
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# app other useful actions would be performed instead)
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time.sleep(1)
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c.disconnect()
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if __name__ == "__main__":
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main()
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```
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- 使用 python 命令执行上述代码文件，就会连接上 MQTT 服务器，可收到我们从另一个客户端发布的以 `foo_topic`为主题的内容
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#### MQTT 发布功能
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- 执行下面的代码后将向 MQTT 服务器发布以 `foo_topic` 为主题的信息
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```python
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from umqtt.simple import MQTTClient
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# Test reception e.g. with:
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# mosquitto_sub -t foo_topic
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def main(server="iot.eclipse.org"):
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c = MQTTClient("SummerGift", server)
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c.connect()
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c.publish(b"foo_topic", b"Hello RT-Thread !!!")
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c.disconnect()
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if __name__ == "__main__":
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main()
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```
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